All packages come preinstalled in Fedora Workstation. In case you removed them,
run dnf install flatpak xdg-desktop-portal-gtk xdg-desktop-portal gnome-software as root/sudo.
Then restart your computer to add Flatpak paths alongside the system ones. Otherwise,
you may see strange errors. Unfortunately, just logging out and logging in is not enough.

Add Flathub and Nuvola Apps Repositories

The Flathub repository provides GNOME Platform runtime, which is used by Nuvola to share common
dependencies with other Flatpak apps to reduce disk & memory usage. The Nuvola Apps repository
contains Nuvola Apps Service and individual Nuvola web apps.

Install Nuvola Apps Service

Nuvola Apps Service is an optional background service that provides individual Nuvola apps with
global shared resources such as a global configuration storage, global keyboard shortcuts, a HTTP remote control
server, and a command-line controller. While this service is optional, the installation is recommended.

In order to install Nuvola Apps Service with GNOME Software, launch GNOME Software,
search for Nuvola Apps Service and finally click the Install button.